What should I buy in bulk?

An expert explains when bigger really is better — and when it isn't.

Buying a membership to a wholesale shopping club certainly can pay off — but it doesn’t always. Toss giant boxes of this or jumbo-size canisters of that in your cart without giving a second thought to price tags, and you probably won’t save enough to cover the cost of your membership. If you want to save a bundle when you buy in bulk, you need to shop smart — and we have the experts who can tell you how. Read on to learn where the real savings are.

What to buy in bulk

Vitamins: Unlike over-the-counter meds (see below) vitamins are easy to use up by their expiration date, assuming you take them daily. Dr. Philip Trigiani, a healthcare practitioner in New York City, suggests women buy bulk-size bottles of a multivitamin that includes calcium and iron.

Paper goods: Assuming you have the storage space, it’s worth it to stock up on toilet paper and paper towels, says Cathi Brese Doebler, author of "Ditch the Joneses, Discover Your Family: How to Thrive on Less Than Two Incomes!" However, if you don’t have a garage or basement, 30 rolls of either are going to cause more headaches than they’re worth.

Pet food: Unlike people, pets don’t get sick of their food, so you generally can’t go wrong if you buy the biggest-possible bag of kibble, says Brese Doebler. Of course, you’ll need to take your pets’ size and appetite into consideration. By the time your teacup chihuahua gets through the first 10 pounds of a 30-pound bag, what’s left will probably be stale.

Baked goods: Lots of wholesale clubs now have full-service bakeries, says consumer finance expert Kevin Gallegos, vice president of Freedom Debt Relief in Tempe, Ariz. And they don’t only sell supersize boxes of pastries! Order in advance — just as you would at a regular bakery — and you can get a custom-decorated cake (even a wedding cake!) to feed a few people or a crowd.

Canned goods: If you have the storage space for 24 cans of soup or string beans, go ahead and buy them, says Brese Doebler. The key is to buy products you’re familiar with. If you love a certain brand of soup but haven’t tried their clam chowder yet, hold off on buying two dozen cans until you’re sure your family likes it.

Grains: Most families have a go-to grain, like brown rice, that they eat several times a week. Buy dried grains that you’re apt to serve often in bulk for a savings of up to 30 percent, says Todd Kluger of the Bulk Is Green Council. Store bulk grains in heavy plastic or glass containers to keep pests out.

What to consider buying in bulk

Spices: Buy dried spices in bulk and you’ll spend up to 96 percent less than you would if you bought the tiny jars in the supermarket spice section, according to Kluger. Here’s the catch: Dried spices have a shelf life of about a year; if you end up tossing a half-used jumbo-size canister of dried parsley, you’re throwing away money.

Beauty products: Ounce for ounce, you’ll probably spend less on face lotion if you buy a multipack. But check the expiration date. Beauty products are less potent when they’re past their prime, which means ingredients that block sun, smooth wrinkles and so on will be less effective.

Meat and fresh produce: A box of 60 hamburgers or 16 pounds of bananas is great — if you need them. If you don’t, talk to a friend beforehand about splitting extra-large quantities, suggests consumer finance expert Jeanette Pavini. Can’t find a friend to share with? Skip ’em. The bananas will go bad — or your kids will stage a banana strike — and the 50 extra burgers will eventually turn to hockey pucks in your freezer.

Frozen foods: The key to buying frozen foods in bulk is to repackage them, Pavani says. Divide frozen shrimp and such into serving-size bags so you don’t have to keep opening and closing the big bag, letting air in. However, take your freezer into consideration before committing to bulk frozen foods. If yours is circa 1976, anything you store in it for more than a few weeks will probably have freezer burn.

What not to buy in bulk

Pet shampoo: ... or annual plant fertilizer, or anything else you don’t use very often. “While you might find a great deal, you’ll tie up money that could probably be better used elsewhere,” says Gallegos.

Junk food: If you buy a lot of junk, you’re going to eat a lot of junk, says Heather Wheeler, cofounder of Krazy Coupon Lady and coauthor of "Pick Another Checkout Lane, Honey." “I don’t care if the case of 24 candy bars is only 36 cents per bar instead of 50 cents each at the corner grocery store,” she says. “Purchasing chocolate in 5-pound increments is not a good idea for your bottom line or your waistline.”

Anything with a limited shelf life: Peanut butter made with nonhydrogenated oil has a shelf life of under a year, says Wheeler. Unless you have three or four kids, buy natural peanut butter in regular-size jars. She also suggests buying mayonnaise in a small jar, which you should be able to use up before it turns rancid.

Over-the-counter medicine: A bottle with 1,000 ibuprofen tablets probably has a great per-pill price. But check the expiration date. Chances are, it’ll take you five or six years to go through them — and they’ll have expired well before then.

Diapers: If you’re not careful, you could wind up with a few hundred diapers that are too small for Junior. “Kids' growth spurts can mess up the best-laid plans,” says Wheeler. The caveat is that some wholesale clubs will let you exchange sizes, so double-check your club’s policy.

New products: ... or new varieties of your favorites. Wheeler’s kids, for example, love Quaker Instant Oatmeal, so when she found a great deal on the new Quaker High-Fiber Instant Oatmeal, she bought in bulk ... only to find out that the extra fiber didn’t agree with her children’s stomachs.

Breakfast cereal: Wholesale clubs often charge as much as $8 for a two-pack of dry cereal. “I swear those are the biggest rip-off,” says Wheeler. Shop sales and use coupons, and you can usually get a box of name-brand cereal for under a buck, she says.

This article originally appeared on WomansDay.com and is republished here with permission.